A man from Pennsylvania is suing Walmart (WMT) over claims that Walmart doesn’t recalculate taxes when its consumers use coupons.

Consumerist reports that the plaintiff used a “Buy one, get one free” coupon when purchasing two cans of shaving cream in Pittsburgh, but Walmart still charged him the sales tax of two cans. The law regarding how taxes are calculated after coupons varies from state to state, but Pennsylvania law states that the 7% tax must be applied to discounted prices.

The lawsuit is looking to add consumers who have used coupons in Pennsylvania Walmarts since June 2007. The retail giants could be in trouble if found guilty since it is estimated that there are hundreds of thousands of people that could fit into this category.

Despite these allegations, Walmart claims that it has previously confirmed with the state that it has been complying with Pennsylvania’s tax laws.